1. Field of the Invention
The present invention relates to an image reading apparatus which is applicable to an image forming apparatus such as a scanner, a copying machine, and a facsimile (FAX), particularly relates to an image reading apparatus and an image reading method, which simultaneously read images on both sides of an original by the use of two reading means.
2. Related Background Art
In an image reading portion (reader portion) of the conventional image forming apparatus such as the copying machine, an image reading apparatus of the reducing optical system, which comprises four components of a carriage storing a light source for illuminating an original from a lower side of a copy board glass, a light reflector for condensing a light beam of the light source onto the original, and a mirror, a carriage for storing two mirrors reflecting the light beam reflected on the above-described mirror toward a predetermined direction, a lens for condensing the reflected light beam or the projected light beam from the original, which is reflected with the two mirrors, and a CCD sensor for receiving the reflected light beam or the projected light from the original, which is condensed with the above-described lens, or the image reading apparatus using single reading sensor such as an image reading apparatus of an one-power optical system which utilizes an LED array light source, a rod lens array, and a Contact Image Sensor (CIS) to read the image in intimate contact with the original is used.
In these image reading apparatuses, in the case that the images on both sides of the original are read, a top surface and a back surface of the both-side original are alternately read by the use of means for reversing an original such as a Document Feeder (DF). However, recently an image reading apparatus having a mechanism which simultaneously reads the both sides has been proposed as shown in FIG. 5.
FIG. 5 is a sectional view showing a schematic structure of the image reading apparatus, and mainly shows a reading position of the both sides of the original and a layout of a conveying path. In FIG. 5, reference numeral 101 indicates a CCD sensor, 102 indicates CIS, 103 indicates a reference white plate, 104 indicates a white sheet, and 105 indicates a copy board, respectively.
The image reading apparatus having the above-described structure includes a first reading sensor (CCD sensor 101) for reading a top surface (first plane) of the original and a second reading sensor (CIS 102) for reading a back surface (second plane) of the same original, and has the mechanism in which the both sides of the original are read in one time conveyance with the first reading sensor and the second reading sensor in course of the conveyance of the original put on the copy board 105 to a discharge side.
However, since original scanning speed of the one-power optical system with CIS is generally slower than the scanning speed of the reducing optical system with the CCD sensor, in the mechanism which reads the both sides by the use of the above-described paper feeding, the scanning speed of the reducing optical system with the CCD sensor is reduced to the scanning speed of the one-power optical system with CIS, the scanning speed of the reducing optical system matches to that of the one-power optical system, and the images on both sides of the original must be simultaneously read.
Accordingly, in the case that the scanning speed of the optical system with the CCD sensor and that of the optical system with CIS are equally set, even in the case that the single-side image original is read with the reducing optical system with the CCD sensor, there is a problem that the original must be scanned at scanning speed of the one-power optical system with CIS, which is slower than the performance of the reducing optical system with the CCD sensor.
In view of the foregoing problem, the present invention is directed at providing an image reading apparatus with high productivity, a control method thereof, and an image forming apparatus, in which the image reading can be performed at optimum original scanning speed in the both-side reading and the single-side reading and the image reading can be performed at optimum original scanning speed even if the image reading apparatus reads the original which is not specified whether the original is the single-side image or the both-side image.
It is an object of the present invention is to provide an image reading apparatus including conveying means which conveys an original to a first reading position and a second reading position, first reading means which reads a first surface of the original at the first reading position while the original is conveyed with the conveying means, second reading means which reads a second surface of the original at the second reading position while the original is conveyed with the conveying means, a first reading mode which reads a single side of the original to be conveyed with the conveying means with the first reading means, a second reading mode which reads both sides of the original to be conveyed with the conveying means with the first reading means and the second reading means, setting means which sets the first reading mode or the second reading mode, and control means which controls to read the both sides of the original for a first original in the case that the first reading mode or the second reading mode is not set with the setting means, to read the single side of the original for second and subsequent originals in the case that an image of the first original is in the singe side, and to read the both sides of the original for the second and subsequent originals in the case that the image of the first original is in the both sides.
Another object of the present invention is to provide an image reading apparatus wherein a first original conveying speed in the first reading mode is faster than a second original conveying speed in the second reading mode.
A further object of the present invention is to provide an image reading apparatus wherein the first reading means includes an image reading unit of a reducing optical system and the second reading means includes an image reading unit of a one-power optical system.
A further object of the present invention is to provide an image reading apparatus wherein the first reading means and the second reading means include the image reading unit of the one-power optical system.
A further object of the present invention is to provide an image reading apparatus including conveying means which conveys an original to a first reading position and a second reading position, first reading means which reads a first surface of the original at the first reading position while the original is conveyed with the conveying means, second reading means which reads a second surface of the original at the second reading position while the original is conveyed with the conveying means, a first reading mode which reads a single side of the original to be conveyed with the conveying means with the first reading means, a second reading mode which reads both sides of the original to be conveyed with the conveying means with the first reading means and the second reading means, setting means which sets the first reading mode or the second reading mode, and control means which controls to read the both sides of the original for a first original in the case that the first reading mode or the second reading mode is not set with the setting means.
A further object of the present invention is to provide an image reading apparatus including a first original conveying speed in the first reading mode is faster than a second original conveying speed in the second reading mode.,
A further object of the present invention is to provide an image reading apparatus including the first reading means includes an image reading unit of a reducing optical system and the second reading means includes an image reading unit of a one-power optical system.
A further object of the present invention is to provide an image reading apparatus including the first reading means and the second reading means include the image reading unit of the one-power optical system.
A further object of the present invention is to provide an image reading apparatus including conveying means which conveys an original, a first reading mode which reads a single side of the original which is conveyed with the conveying means, a second reading mode which reads both sides of the original to be conveyed with the conveying means, setting means which sets the first reading mode or the second reading mode, and control means which controls to read the both sides of the original for a first original in the case that the first reading mode or the second reading mode is not set with the setting means, to read the single side of the original for second and subsequent originals in the case that an image of the first original is in the singe side, and to read the both sides of the original for the second and subsequent originals in the case that the image of the first original is in the both sides.
A still further object of the present invention is to provide an image reading apparatus including the steps of setting a first reading mode for reading a single side of an original or a second reading mode for reading both sides of the original, starting the reading of the original, conveying a plurality of originals one by one on the basis of instruction by the starting step, and reading the both sides of the original for a first original in the case that the first reading mode or the second reading mode is not set with the setting step, reading the single side of the original for second and subsequent originals in the case that an image of the first original is in the singe side, and reading the both sides of the original for the second and subsequent originals in the case that the image of the first original is in the both sides.
Other objects and features of the present invention will become apparent from the following description and drawings.